Emission abatement devices are used to treat emissions present in exhaust gas. For example, there are NOx traps, particulate filters, and selective catalytic reduction (SCR) devices. From time to time, NOx traps and particulate filters may need to be “regenerated” to purge them of emissions trapped thereby. A regenerative agent may be injected into the exhaust gas to facilitate such regeneration. In addition, there are SCR devices which operate in conjunction with an agent injected into the exhaust gas stream to facilitate removal of NOx therefrom. This application relates to enhancements in the injection of regenerative agents and other agents into the exhaust gas for use with emission abatement devices.